Sir Malcolm Rifkind, the former foreign secretary, has resigned as honorary president of the Conservative Friends of Russia (CFOR) group over the group's spat with Labour MP Chris Bryant this week.

A spokesman for Sir Malcolm said he was "very unhappy" about the article that was run by CFOR this week and it was the "final straw", adding to long-held concerns about the way the group was being run.

He said the article was a "personal attack over a trivial matter".

Conservative Friends of Russia insists it receives no funding from the Russian state. The original write-up of their launch event described it as 'sinister' and the ongoing communications meltdown that the group has gone through this week (a Twitter and blogging spat aimed at Chris Bryant MP - a vocal critic of Vladimir Putin) will again raise questions about the groups motives.

A CFOR blog this week accused Mr. Bryant of not sticking a set of rules regarding his Russia All Party Parliamentary group. When the piece was posted, the MP challenged the Friends of Russia group in an angry exchange on Twitter.

CFOR chose to run an image of the homosexual MP in his underwear. 

Mr Bryant wrote: "I gather the Conservative Friends of Russia have covered themselves in homophobic glory.

"Clearly [they] would prefer a Putin patsy to run the all party group on Russia. Did the Embassy pay for them?"

The website then replaced the picture with one featuring Mr Bryant fully-clothed.

Mr Bryant has long been critical of Mr Putin's leadership. He is known for his fierce criticisms of the Putin regime's stance on homosexual rights and its "disgraceful intransigence" over Syria.